2 * Copyright (C) 1995-2008 University of Karlsruhe. All right reserved.
4 * This file is part of libFirm.
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * @brief Load/Store optimizations.
23 * @author Michael Beck
32 #include "iroptimize.h"
34 #include "irgraph_t.h"
42 #include "dbginfo_t.h"
43 #include "iropt_dbg.h"
49 #include "opt_polymorphy.h"
51 #include "irphase_t.h"
55 /** The debug handle. */
56 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
59 #include "cacheopt/cachesim.h"
63 #define IMAX(a,b) ((a) > (b) ? (a) : (b))
65 #define MAX_PROJ IMAX(IMAX(pn_Load_max, pn_Store_max), pn_Call_max)
68 DF_CHANGED = 1, /**< data flow changed */
69 CF_CHANGED = 2, /**< control flow changed */
75 typedef struct _walk_env_t {
76 struct obstack obst; /**< list of all stores */
77 unsigned changes; /**< a bitmask of graph changes */
80 /** A Load/Store info. */
81 typedef struct _ldst_info_t {
82 ir_node *projs[MAX_PROJ]; /**< list of Proj's of this node */
83 ir_node *exc_block; /**< the exception block if available */
84 int exc_idx; /**< predecessor index in the exception block */
85 unsigned visited; /**< visited counter for breaking loops */
89 * flags for control flow.
92 BLOCK_HAS_COND = 1, /**< Block has conditional control flow */
93 BLOCK_HAS_EXC = 2 /**< Block has exceptional control flow */
99 typedef struct _block_info_t {
100 unsigned flags; /**< flags for the block */
103 /** the master visited flag for loop detection. */
104 static unsigned master_visited = 0;
106 #define INC_MASTER() ++master_visited
107 #define MARK_NODE(info) (info)->visited = master_visited
108 #define NODE_VISITED(info) (info)->visited >= master_visited
111 * get the Load/Store info of a node
113 static ldst_info_t *get_ldst_info(ir_node *node, struct obstack *obst) {
114 ldst_info_t *info = get_irn_link(node);
117 info = obstack_alloc(obst, sizeof(*info));
118 memset(info, 0, sizeof(*info));
119 set_irn_link(node, info);
122 } /* get_ldst_info */
125 * get the Block info of a node
127 static block_info_t *get_block_info(ir_node *node, struct obstack *obst) {
128 block_info_t *info = get_irn_link(node);
131 info = obstack_alloc(obst, sizeof(*info));
132 memset(info, 0, sizeof(*info));
133 set_irn_link(node, info);
136 } /* get_block_info */
139 * update the projection info for a Load/Store
141 static unsigned update_projs(ldst_info_t *info, ir_node *proj)
143 long nr = get_Proj_proj(proj);
145 assert(0 <= nr && nr <= MAX_PROJ && "Wrong proj from LoadStore");
147 if (info->projs[nr]) {
148 /* there is already one, do CSE */
149 exchange(proj, info->projs[nr]);
153 info->projs[nr] = proj;
159 * update the exception block info for a Load/Store node.
161 * @param info the load/store info struct
162 * @param block the exception handler block for this load/store
163 * @param pos the control flow input of the block
165 static unsigned update_exc(ldst_info_t *info, ir_node *block, int pos)
167 assert(info->exc_block == NULL && "more than one exception block found");
169 info->exc_block = block;
174 /** Return the number of uses of an address node */
175 #define get_irn_n_uses(adr) get_irn_n_edges(adr)
178 * walker, collects all Load/Store/Proj nodes
180 * walks from Start -> End
182 static void collect_nodes(ir_node *node, void *env)
184 ir_opcode opcode = get_irn_opcode(node);
185 ir_node *pred, *blk, *pred_blk;
186 ldst_info_t *ldst_info;
187 walk_env_t *wenv = env;
189 if (opcode == iro_Proj) {
190 pred = get_Proj_pred(node);
191 opcode = get_irn_opcode(pred);
193 if (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call) {
194 ldst_info = get_ldst_info(pred, &wenv->obst);
196 wenv->changes |= update_projs(ldst_info, node);
199 * Place the Proj's to the same block as the
200 * predecessor Load. This is always ok and prevents
201 * "non-SSA" form after optimizations if the Proj
202 * is in a wrong block.
204 blk = get_nodes_block(node);
205 pred_blk = get_nodes_block(pred);
206 if (blk != pred_blk) {
207 wenv->changes |= DF_CHANGED;
208 set_nodes_block(node, pred_blk);
211 } else if (opcode == iro_Block) {
214 for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
215 ir_node *pred_block, *proj;
216 block_info_t *bl_info;
219 pred = proj = get_Block_cfgpred(node, i);
222 pred = get_Proj_pred(proj);
223 is_exc = get_Proj_proj(proj) == pn_Generic_X_except;
226 /* ignore Bad predecessors, they will be removed later */
230 pred_block = get_nodes_block(pred);
231 bl_info = get_block_info(pred_block, &wenv->obst);
233 if (is_fragile_op(pred) && is_exc)
234 bl_info->flags |= BLOCK_HAS_EXC;
235 else if (is_irn_forking(pred))
236 bl_info->flags |= BLOCK_HAS_COND;
238 opcode = get_irn_opcode(pred);
239 if (is_exc && (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call)) {
240 ldst_info = get_ldst_info(pred, &wenv->obst);
242 wenv->changes |= update_exc(ldst_info, node, i);
246 } /* collect_nodes */
249 * Returns an entity if the address ptr points to a constant one.
251 * @param ptr the address
253 * @return an entity or NULL
255 static ir_entity *find_constant_entity(ir_node *ptr)
258 if (is_SymConst(ptr) && get_SymConst_kind(ptr) == symconst_addr_ent) {
259 return get_SymConst_entity(ptr);
260 } else if (is_Sel(ptr)) {
261 ir_entity *ent = get_Sel_entity(ptr);
262 ir_type *tp = get_entity_owner(ent);
264 /* Do not fiddle with polymorphism. */
265 if (is_Class_type(get_entity_owner(ent)) &&
266 ((get_entity_n_overwrites(ent) != 0) ||
267 (get_entity_n_overwrittenby(ent) != 0) ) )
270 if (is_Array_type(tp)) {
274 for (i = 0, n = get_Sel_n_indexs(ptr); i < n; ++i) {
276 tarval *tlower, *tupper;
277 ir_node *index = get_Sel_index(ptr, i);
278 tarval *tv = computed_value(index);
280 /* check if the index is constant */
281 if (tv == tarval_bad)
284 bound = get_array_lower_bound(tp, i);
285 tlower = computed_value(bound);
286 bound = get_array_upper_bound(tp, i);
287 tupper = computed_value(bound);
289 if (tlower == tarval_bad || tupper == tarval_bad)
292 if (tarval_cmp(tv, tlower) & pn_Cmp_Lt)
294 if (tarval_cmp(tupper, tv) & pn_Cmp_Lt)
297 /* ok, bounds check finished */
301 if (variability_constant == get_entity_variability(ent))
305 ptr = get_Sel_ptr(ptr);
306 } else if (is_Add(ptr)) {
307 ir_node *l = get_Add_left(ptr);
308 ir_node *r = get_Add_right(ptr);
310 if (get_irn_mode(l) == get_irn_mode(ptr) && is_Const(r))
312 else if (get_irn_mode(r) == get_irn_mode(ptr) && is_Const(l))
317 /* for now, we support only one addition, reassoc should fold all others */
318 if (! is_SymConst(ptr) && !is_Sel(ptr))
320 } else if (is_Sub(ptr)) {
321 ir_node *l = get_Sub_left(ptr);
322 ir_node *r = get_Sub_right(ptr);
324 if (get_irn_mode(l) == get_irn_mode(ptr) && is_Const(r))
328 /* for now, we support only one substraction, reassoc should fold all others */
329 if (! is_SymConst(ptr) && !is_Sel(ptr))
334 } /* find_constant_entity */
337 * Return the Selection index of a Sel node from dimension n
339 static long get_Sel_array_index_long(ir_node *n, int dim) {
340 ir_node *index = get_Sel_index(n, dim);
341 assert(is_Const(index));
342 return get_tarval_long(get_Const_tarval(index));
343 } /* get_Sel_array_index_long */
346 * Returns the accessed component graph path for an
347 * node computing an address.
349 * @param ptr the node computing the address
350 * @param depth current depth in steps upward from the root
353 static compound_graph_path *rec_get_accessed_path(ir_node *ptr, int depth) {
354 compound_graph_path *res = NULL;
355 ir_entity *root, *field, *ent;
356 int path_len, pos, idx;
360 if (is_SymConst(ptr)) {
361 /* a SymConst. If the depth is 0, this is an access to a global
362 * entity and we don't need a component path, else we know
363 * at least its length.
365 assert(get_SymConst_kind(ptr) == symconst_addr_ent);
366 root = get_SymConst_entity(ptr);
367 res = (depth == 0) ? NULL : new_compound_graph_path(get_entity_type(root), depth);
368 } else if (is_Sel(ptr)) {
369 /* it's a Sel, go up until we find the root */
370 res = rec_get_accessed_path(get_Sel_ptr(ptr), depth+1);
374 /* fill up the step in the path at the current position */
375 field = get_Sel_entity(ptr);
376 path_len = get_compound_graph_path_length(res);
377 pos = path_len - depth - 1;
378 set_compound_graph_path_node(res, pos, field);
380 if (is_Array_type(get_entity_owner(field))) {
381 assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
382 set_compound_graph_path_array_index(res, pos, get_Sel_array_index_long(ptr, 0));
384 } else if (is_Add(ptr)) {
385 ir_node *l = get_Add_left(ptr);
386 ir_node *r = get_Add_right(ptr);
387 ir_mode *mode = get_irn_mode(ptr);
390 if (is_Const(r) && get_irn_mode(l) == mode) {
392 tv = get_Const_tarval(r);
395 tv = get_Const_tarval(l);
398 mode = get_tarval_mode(tv);
401 /* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
403 field = get_Sel_entity(ptr);
405 field = get_SymConst_entity(ptr);
408 for (ent = field;;) {
410 tarval *sz, *tv_index, *tlower, *tupper;
413 tp = get_entity_type(ent);
414 if (! is_Array_type(tp))
416 ent = get_array_element_entity(tp);
417 size = get_type_size_bytes(get_entity_type(ent));
418 sz = new_tarval_from_long(size, mode);
420 tv_index = tarval_div(tmp, sz);
421 tmp = tarval_mod(tmp, sz);
423 if (tv_index == tarval_bad || tmp == tarval_bad)
426 assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
427 bound = get_array_lower_bound(tp, 0);
428 tlower = computed_value(bound);
429 bound = get_array_upper_bound(tp, 0);
430 tupper = computed_value(bound);
432 if (tlower == tarval_bad || tupper == tarval_bad)
435 if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
437 if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
440 /* ok, bounds check finished */
443 if (! tarval_is_null(tmp)) {
444 /* access to some struct/union member */
448 /* should be at least ONE array */
452 res = rec_get_accessed_path(ptr, depth + idx);
456 path_len = get_compound_graph_path_length(res);
457 pos = path_len - depth - idx;
459 for (ent = field;;) {
461 tarval *sz, *tv_index;
464 tp = get_entity_type(ent);
465 if (! is_Array_type(tp))
467 ent = get_array_element_entity(tp);
468 set_compound_graph_path_node(res, pos, ent);
470 size = get_type_size_bytes(get_entity_type(ent));
471 sz = new_tarval_from_long(size, mode);
473 tv_index = tarval_div(tv, sz);
474 tv = tarval_mod(tv, sz);
476 /* worked above, should work again */
477 assert(tv_index != tarval_bad && tv != tarval_bad);
479 /* bounds already checked above */
480 index = get_tarval_long(tv_index);
481 set_compound_graph_path_array_index(res, pos, index);
484 } else if (is_Sub(ptr)) {
485 ir_node *l = get_Sub_left(ptr);
486 ir_node *r = get_Sub_right(ptr);
489 tv = get_Const_tarval(r);
494 } /* rec_get_accessed_path */
497 * Returns an access path or NULL. The access path is only
498 * valid, if the graph is in phase_high and _no_ address computation is used.
500 static compound_graph_path *get_accessed_path(ir_node *ptr) {
501 compound_graph_path *gr = rec_get_accessed_path(ptr, 0);
503 } /* get_accessed_path */
505 typedef struct path_entry {
507 struct path_entry *next;
511 static ir_node *rec_find_compound_ent_value(ir_node *ptr, path_entry *next) {
512 path_entry entry, *p;
513 ir_entity *ent, *field;
514 ir_initializer_t *initializer;
520 if (is_SymConst(ptr)) {
522 ent = get_SymConst_entity(ptr);
523 initializer = get_entity_initializer(ent);
524 for (p = next; p != NULL;) {
525 if (initializer->kind != IR_INITIALIZER_COMPOUND)
527 n = get_initializer_compound_n_entries(initializer);
528 tp = get_entity_type(ent);
530 if (is_Array_type(tp)) {
531 ent = get_array_element_entity(tp);
536 initializer = get_initializer_compound_value(initializer, 0);
540 if (p->index >= (int) n)
542 initializer = get_initializer_compound_value(initializer, p->index);
547 tp = get_entity_type(ent);
548 while (is_Array_type(tp)) {
549 ent = get_array_element_entity(tp);
550 tp = get_entity_type(ent);
552 n = get_initializer_compound_n_entries(initializer);
555 initializer = get_initializer_compound_value(initializer, 0);
558 switch (initializer->kind) {
559 case IR_INITIALIZER_CONST:
560 return get_initializer_const_value(initializer);
561 case IR_INITIALIZER_TARVAL:
562 case IR_INITIALIZER_NULL:
566 } else if (is_Sel(ptr)) {
567 entry.ent = field = get_Sel_entity(ptr);
568 tp = get_entity_owner(field);
569 if (is_Array_type(tp)) {
570 assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
571 entry.index = get_Sel_array_index_long(ptr, 0) - get_array_lower_bound_int(tp, 0);
573 int i, n_members = get_compound_n_members(tp);
574 for (i = 0; i < n_members; ++i) {
575 if (get_compound_member(tp, i) == field)
578 if (i >= n_members) {
579 /* not found: should NOT happen */
584 return rec_find_compound_ent_value(get_Sel_ptr(ptr), &entry);
585 } else if (is_Add(ptr)) {
586 ir_node *l = get_Add_left(ptr);
587 ir_node *r = get_Add_right(ptr);
593 tv = get_Const_tarval(r);
596 tv = get_Const_tarval(l);
599 mode = get_tarval_mode(tv);
601 /* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
603 field = get_Sel_entity(ptr);
605 field = get_SymConst_entity(ptr);
608 /* count needed entries */
610 for (ent = field;;) {
611 tp = get_entity_type(ent);
612 if (! is_Array_type(tp))
614 ent = get_array_element_entity(tp);
617 /* should be at least ONE entry */
621 /* allocate the right number of entries */
622 NEW_ARR_A(path_entry, p, pos);
626 for (ent = field;;) {
628 tarval *sz, *tv_index, *tlower, *tupper;
632 tp = get_entity_type(ent);
633 if (! is_Array_type(tp))
635 ent = get_array_element_entity(tp);
637 p[pos].next = &p[pos + 1];
639 size = get_type_size_bytes(get_entity_type(ent));
640 sz = new_tarval_from_long(size, mode);
642 tv_index = tarval_div(tv, sz);
643 tv = tarval_mod(tv, sz);
645 if (tv_index == tarval_bad || tv == tarval_bad)
648 assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
649 bound = get_array_lower_bound(tp, 0);
650 tlower = computed_value(bound);
651 bound = get_array_upper_bound(tp, 0);
652 tupper = computed_value(bound);
654 if (tlower == tarval_bad || tupper == tarval_bad)
657 if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
659 if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
662 /* ok, bounds check finished */
663 index = get_tarval_long(tv_index);
664 p[pos].index = index;
667 if (! tarval_is_null(tv)) {
668 /* hmm, wrong access */
671 p[pos - 1].next = next;
672 return rec_find_compound_ent_value(ptr, p);
673 } else if (is_Sub(ptr)) {
674 ir_node *l = get_Sub_left(ptr);
675 ir_node *r = get_Sub_right(ptr);
678 tv = get_Const_tarval(r);
685 static ir_node *find_compound_ent_value(ir_node *ptr) {
686 return rec_find_compound_ent_value(ptr, NULL);
690 static void reduce_adr_usage(ir_node *ptr);
693 * Update a Load that may have lost its users.
695 static void handle_load_update(ir_node *load) {
696 ldst_info_t *info = get_irn_link(load);
698 /* do NOT touch volatile loads for now */
699 if (get_Load_volatility(load) == volatility_is_volatile)
702 if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
703 ir_node *ptr = get_Load_ptr(load);
704 ir_node *mem = get_Load_mem(load);
706 /* a Load whose value is neither used nor exception checked, remove it */
707 exchange(info->projs[pn_Load_M], mem);
708 if (info->projs[pn_Load_X_regular])
709 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
711 reduce_adr_usage(ptr);
713 } /* handle_load_update */
716 * A use of an address node has vanished. Check if this was a Proj
717 * node and update the counters.
719 static void reduce_adr_usage(ir_node *ptr) {
721 if (get_irn_n_edges(ptr) <= 0) {
722 /* this Proj is dead now */
723 ir_node *pred = get_Proj_pred(ptr);
726 ldst_info_t *info = get_irn_link(pred);
727 info->projs[get_Proj_proj(ptr)] = NULL;
729 /* this node lost its result proj, handle that */
730 handle_load_update(pred);
734 } /* reduce_adr_usage */
737 * Check, if an already existing value of mode old_mode can be converted
738 * into the needed one new_mode without loss.
740 static int can_use_stored_value(ir_mode *old_mode, ir_mode *new_mode) {
741 if (old_mode == new_mode)
744 /* if both modes are two-complement ones, we can always convert the
745 Stored value into the needed one. */
746 if (get_mode_size_bits(old_mode) >= get_mode_size_bits(new_mode) &&
747 get_mode_arithmetic(old_mode) == irma_twos_complement &&
748 get_mode_arithmetic(new_mode) == irma_twos_complement)
751 } /* can_use_stored_value */
754 * Check whether a Call is at least pure, ie. does only read memory.
756 static unsigned is_Call_pure(ir_node *call) {
757 ir_type *call_tp = get_Call_type(call);
758 unsigned prop = get_method_additional_properties(call_tp);
760 /* check first the call type */
761 if ((prop & (mtp_property_const|mtp_property_pure)) == 0) {
762 /* try the called entity */
763 ir_node *ptr = get_Call_ptr(call);
765 if (is_Global(ptr)) {
766 ir_entity *ent = get_Global_entity(ptr);
768 prop = get_entity_additional_properties(ent);
771 return (prop & (mtp_property_const|mtp_property_pure)) != 0;
774 static ir_node *get_base_and_offset(ir_node *ptr, long *pOffset)
776 ir_mode *mode = get_irn_mode(ptr);
779 /* TODO: long might not be enough, we should probably use some tarval thingy... */
782 ir_node *l = get_Add_left(ptr);
783 ir_node *r = get_Add_right(ptr);
785 if (get_irn_mode(l) != mode || !is_Const(r))
788 offset += get_tarval_long(get_Const_tarval(r));
790 } else if (is_Sub(ptr)) {
791 ir_node *l = get_Sub_left(ptr);
792 ir_node *r = get_Sub_right(ptr);
794 if (get_irn_mode(l) != mode || !is_Const(r))
797 offset -= get_tarval_long(get_Const_tarval(r));
799 } else if (is_Sel(ptr)) {
800 ir_entity *ent = get_Sel_entity(ptr);
801 ir_type *tp = get_entity_owner(ent);
803 if (is_Array_type(tp)) {
807 /* only one dimensional arrays yet */
808 if (get_Sel_n_indexs(ptr) != 1)
810 index = get_Sel_index(ptr, 0);
811 if (! is_Const(index))
814 tp = get_entity_type(ent);
815 if (get_type_state(tp) != layout_fixed)
818 size = get_type_size_bytes(tp);
819 offset += size * get_tarval_long(get_Const_tarval(index));
821 if (get_type_state(tp) != layout_fixed)
823 offset += get_entity_offset(ent);
825 ptr = get_Sel_ptr(ptr);
834 static int try_load_after_store(ir_node *load,
835 ir_node *load_base_ptr, long load_offset, ir_node *store)
838 ir_node *store_ptr = get_Store_ptr(store);
840 ir_node *store_base_ptr = get_base_and_offset(store_ptr, &store_offset);
841 ir_node *store_value;
850 if (load_base_ptr != store_base_ptr)
853 load_mode = get_Load_mode(load);
854 load_mode_len = get_mode_size_bytes(load_mode);
855 store_mode = get_irn_mode(get_Store_value(store));
856 store_mode_len = get_mode_size_bytes(store_mode);
857 delta = load_offset - store_offset;
858 if (delta < 0 || delta + load_mode_len > store_mode_len)
861 if (get_mode_arithmetic(store_mode) != irma_twos_complement ||
862 get_mode_arithmetic(load_mode) != irma_twos_complement)
865 store_value = get_Store_value(store);
867 /* produce a shift to adjust offset delta */
871 /* FIXME: only true for little endian */
872 cnst = new_Const_long(mode_Iu, delta * 8);
873 store_value = new_r_Shr(current_ir_graph, get_nodes_block(load),
874 store_value, cnst, store_mode);
877 /* add an convert if needed */
878 if (store_mode != load_mode) {
879 store_value = new_r_Conv(current_ir_graph, get_nodes_block(load),
880 store_value, load_mode);
883 DBG_OPT_RAW(load, store_value);
885 info = get_irn_link(load);
886 if (info->projs[pn_Load_M])
887 exchange(info->projs[pn_Load_M], get_Load_mem(load));
891 if (info->projs[pn_Load_X_except]) {
892 exchange( info->projs[pn_Load_X_except], new_Bad());
895 if (info->projs[pn_Load_X_regular]) {
896 exchange( info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
900 if (info->projs[pn_Load_res])
901 exchange(info->projs[pn_Load_res], store_value);
903 load_ptr = get_Load_ptr(load);
905 reduce_adr_usage(load_ptr);
906 return res | DF_CHANGED;
910 * Follow the memory chain as long as there are only Loads,
911 * alias free Stores, and constant Calls and try to replace the
912 * current Load by a previous ones.
913 * Note that in unreachable loops it might happen that we reach
914 * load again, as well as we can fall into a cycle.
915 * We break such cycles using a special visited flag.
917 * INC_MASTER() must be called before dive into
919 static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
921 ldst_info_t *info = get_irn_link(load);
923 ir_node *ptr = get_Load_ptr(load);
924 ir_node *mem = get_Load_mem(load);
925 ir_mode *load_mode = get_Load_mode(load);
927 for (pred = curr; load != pred; ) {
928 ldst_info_t *pred_info = get_irn_link(pred);
931 * a Load immediately after a Store -- a read after write.
932 * We may remove the Load, if both Load & Store does not have an
933 * exception handler OR they are in the same MacroBlock. In the latter
934 * case the Load cannot throw an exception when the previous Store was
937 * Why we need to check for Store Exception? If the Store cannot
938 * be executed (ROM) the exception handler might simply jump into
939 * the load MacroBlock :-(
940 * We could make it a little bit better if we would know that the
941 * exception handler of the Store jumps directly to the end...
943 if (is_Store(pred) && ((pred_info->projs[pn_Store_X_except] == NULL
944 && info->projs[pn_Load_X_except] == NULL)
945 || get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)))
948 ir_node *base_ptr = get_base_and_offset(ptr, &load_offset);
949 int changes = try_load_after_store(load, base_ptr, load_offset, pred);
952 return res | changes;
953 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
954 can_use_stored_value(get_Load_mode(pred), load_mode)) {
956 * a Load after a Load -- a read after read.
957 * We may remove the second Load, if it does not have an exception handler
958 * OR they are in the same MacroBlock. In the later case the Load cannot
959 * throw an exception when the previous Load was quiet.
961 * Here, there is no need to check if the previous Load has an exception
962 * hander because they would have exact the same exception...
964 if (info->projs[pn_Load_X_except] == NULL || get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)) {
967 DBG_OPT_RAR(load, pred);
969 /* the result is used */
970 if (info->projs[pn_Load_res]) {
971 if (pred_info->projs[pn_Load_res] == NULL) {
972 /* create a new Proj again */
973 pred_info->projs[pn_Load_res] = new_r_Proj(current_ir_graph, get_nodes_block(pred), pred, get_Load_mode(pred), pn_Load_res);
975 value = pred_info->projs[pn_Load_res];
977 /* add an convert if needed */
978 if (get_Load_mode(pred) != load_mode) {
979 value = new_r_Conv(current_ir_graph, get_nodes_block(load), value, load_mode);
982 exchange(info->projs[pn_Load_res], value);
985 if (info->projs[pn_Load_M])
986 exchange(info->projs[pn_Load_M], mem);
989 if (info->projs[pn_Load_X_except]) {
990 exchange(info->projs[pn_Load_X_except], new_Bad());
993 if (info->projs[pn_Load_X_regular]) {
994 exchange( info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
999 reduce_adr_usage(ptr);
1000 return res |= DF_CHANGED;
1004 if (is_Store(pred)) {
1005 /* check if we can pass through this store */
1006 ir_alias_relation rel = get_alias_relation(
1008 get_Store_ptr(pred),
1009 get_irn_mode(get_Store_value(pred)),
1011 /* if the might be an alias, we cannot pass this Store */
1012 if (rel != ir_no_alias)
1014 pred = skip_Proj(get_Store_mem(pred));
1015 } else if (is_Load(pred)) {
1016 pred = skip_Proj(get_Load_mem(pred));
1017 } else if (is_Call(pred)) {
1018 if (is_Call_pure(pred)) {
1019 /* The called graph is at least pure, so there are no Store's
1020 in it. We can handle it like a Load and skip it. */
1021 pred = skip_Proj(get_Call_mem(pred));
1023 /* there might be Store's in the graph, stop here */
1027 /* follow only Load chains */
1031 /* check for cycles */
1032 if (NODE_VISITED(pred_info))
1034 MARK_NODE(pred_info);
1037 if (is_Sync(pred)) {
1040 /* handle all Sync predecessors */
1041 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
1042 res |= follow_Mem_chain(load, skip_Proj(get_Sync_pred(pred, i)));
1049 } /* follow_Mem_chain */
1052 * Check if we can replace the load by a given const from
1053 * the const code irg.
1055 ir_node *can_replace_load_by_const(const ir_node *load, ir_node *c) {
1056 ir_mode *c_mode = get_irn_mode(c);
1057 ir_mode *l_mode = get_Load_mode(load);
1058 ir_node *res = NULL;
1060 if (c_mode != l_mode) {
1061 /* check, if the mode matches OR can be easily converted info */
1062 if (is_reinterpret_cast(c_mode, l_mode)) {
1063 /* we can safely cast */
1064 dbg_info *dbg = get_irn_dbg_info(load);
1065 ir_node *block = get_nodes_block(load);
1067 /* copy the value from the const code irg and cast it */
1068 res = copy_const_value(dbg, c);
1069 res = new_rd_Conv(dbg, current_ir_graph, block, res, l_mode);
1072 /* copy the value from the const code irg */
1073 res = copy_const_value(get_irn_dbg_info(load), c);
1076 } /* can_replace_load_by_const */
1081 * @param load the Load node
1083 static unsigned optimize_load(ir_node *load)
1085 ldst_info_t *info = get_irn_link(load);
1086 ir_node *mem, *ptr, *value;
1091 /* do NOT touch volatile loads for now */
1092 if (get_Load_volatility(load) == volatility_is_volatile)
1095 /* the address of the load to be optimized */
1096 ptr = get_Load_ptr(load);
1099 * Check if we can remove the exception from a Load:
1100 * This can be done, if the address is from an Sel(Alloc) and
1101 * the Sel type is a subtype of the allocated type.
1103 * This optimizes some often used OO constructs,
1104 * like x = new O; x->t;
1106 if (info->projs[pn_Load_X_except]) {
1107 ir_node *addr = ptr;
1109 /* find base address */
1110 while (is_Sel(addr))
1111 addr = get_Sel_ptr(addr);
1112 if (is_Alloc(skip_Proj(skip_Cast(addr)))) {
1113 /* simple case: a direct load after an Alloc. Firm Alloc throw
1114 * an exception in case of out-of-memory. So, there is no way for an
1115 * exception in this load.
1116 * This code is constructed by the "exception lowering" in the Jack compiler.
1118 exchange(info->projs[pn_Load_X_except], new_Bad());
1119 info->projs[pn_Load_X_except] = NULL;
1120 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
1121 info->projs[pn_Load_X_regular] = NULL;
1126 /* The mem of the Load. Must still be returned after optimization. */
1127 mem = get_Load_mem(load);
1129 if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
1130 /* a Load which value is neither used nor exception checked, remove it */
1131 exchange(info->projs[pn_Load_M], mem);
1133 if (info->projs[pn_Load_X_regular]) {
1134 /* should not happen, but if it does, remove it */
1135 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
1139 reduce_adr_usage(ptr);
1140 return res | DF_CHANGED;
1143 /* Load from a constant polymorphic field, where we can resolve
1145 value = transform_polymorph_Load(load);
1146 if (value == load) {
1148 /* check if we can determine the entity that will be loaded */
1149 ent = find_constant_entity(ptr);
1151 allocation_static == get_entity_allocation(ent) &&
1152 visibility_external_allocated != get_entity_visibility(ent)) {
1153 /* a static allocation that is not external: there should be NO exception
1154 * when loading even if we cannot replace the load itself. */
1156 /* no exception, clear the info field as it might be checked later again */
1157 if (info->projs[pn_Load_X_except]) {
1158 exchange(info->projs[pn_Load_X_except], new_Bad());
1159 info->projs[pn_Load_X_except] = NULL;
1162 if (info->projs[pn_Load_X_regular]) {
1163 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
1164 info->projs[pn_Load_X_regular] = NULL;
1168 if (variability_constant == get_entity_variability(ent)) {
1169 if (is_atomic_entity(ent)) {
1170 /* Might not be atomic after lowering of Sels. In this case we
1171 * could also load, but it's more complicated. */
1172 /* more simpler case: we load the content of a constant value:
1173 * replace it by the constant itself */
1174 value = get_atomic_ent_value(ent);
1175 } else if (ent->has_initializer) {
1176 /* new style initializer */
1177 value = find_compound_ent_value(ptr);
1179 /* old style initializer */
1180 compound_graph_path *path = get_accessed_path(ptr);
1183 assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1));
1185 value = get_compound_ent_value_by_path(ent, path);
1186 DB((dbg, LEVEL_1, " Constant access at %F%F resulted in %+F\n", ent, path, value));
1187 free_compound_graph_path(path);
1191 value = can_replace_load_by_const(load, value);
1195 if (value != NULL) {
1196 /* we completely replace the load by this value */
1197 if (info->projs[pn_Load_X_except]) {
1198 exchange(info->projs[pn_Load_X_except], new_Bad());
1199 info->projs[pn_Load_X_except] = NULL;
1202 if (info->projs[pn_Load_X_regular]) {
1203 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load)));
1204 info->projs[pn_Load_X_regular] = NULL;
1207 if (info->projs[pn_Load_M]) {
1208 exchange(info->projs[pn_Load_M], mem);
1211 if (info->projs[pn_Load_res]) {
1212 exchange(info->projs[pn_Load_res], value);
1216 reduce_adr_usage(ptr);
1220 /* Check, if the address of this load is used more than once.
1221 * If not, more load cannot be removed in any case. */
1222 if (get_irn_n_uses(ptr) <= 1 && get_irn_n_uses(get_base_and_offset(ptr, &dummy)) <= 1)
1226 * follow the memory chain as long as there are only Loads
1227 * and try to replace current Load or Store by a previous one.
1228 * Note that in unreachable loops it might happen that we reach
1229 * load again, as well as we can fall into a cycle.
1230 * We break such cycles using a special visited flag.
1233 res = follow_Mem_chain(load, skip_Proj(mem));
1235 } /* optimize_load */
1238 * Check whether a value of mode new_mode would completely overwrite a value
1239 * of mode old_mode in memory.
1241 static int is_completely_overwritten(ir_mode *old_mode, ir_mode *new_mode)
1243 return get_mode_size_bits(new_mode) >= get_mode_size_bits(old_mode);
1244 } /* is_completely_overwritten */
1247 * Check whether small is a part of large (starting at same address).
1249 static int is_partially_same(ir_node *small, ir_node *large)
1251 ir_mode *sm = get_irn_mode(small);
1252 ir_mode *lm = get_irn_mode(large);
1254 /* FIXME: Check endianness */
1255 return is_Conv(small) && get_Conv_op(small) == large
1256 && get_mode_size_bytes(sm) < get_mode_size_bytes(lm)
1257 && get_mode_arithmetic(sm) == irma_twos_complement
1258 && get_mode_arithmetic(lm) == irma_twos_complement;
1259 } /* is_partially_same */
1262 * follow the memory chain as long as there are only Loads and alias free Stores.
1264 * INC_MASTER() must be called before dive into
1266 static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr) {
1268 ldst_info_t *info = get_irn_link(store);
1270 ir_node *ptr = get_Store_ptr(store);
1271 ir_node *mem = get_Store_mem(store);
1272 ir_node *value = get_Store_value(store);
1273 ir_mode *mode = get_irn_mode(value);
1274 ir_node *block = get_nodes_block(store);
1275 ir_node *mblk = get_Block_MacroBlock(block);
1277 for (pred = curr; pred != store;) {
1278 ldst_info_t *pred_info = get_irn_link(pred);
1281 * BEWARE: one might think that checking the modes is useless, because
1282 * if the pointers are identical, they refer to the same object.
1283 * This is only true in strong typed languages, not is C were the following
1284 * is possible *(ir_type1 *)p = a; *(ir_type2 *)p = b ...
1285 * However, if the size of the mode that is written is bigger or equal the
1286 * size of the old one, the old value is completely overwritten and can be
1289 if (is_Store(pred) && get_Store_ptr(pred) == ptr &&
1290 get_nodes_MacroBlock(pred) == mblk) {
1292 * a Store after a Store in the same MacroBlock -- a write after write.
1296 * We may remove the first Store, if the old value is completely
1297 * overwritten or the old value is a part of the new value,
1298 * and if it does not have an exception handler.
1300 * TODO: What, if both have the same exception handler ???
1302 if (get_Store_volatility(pred) != volatility_is_volatile
1303 && !pred_info->projs[pn_Store_X_except]) {
1304 ir_node *predvalue = get_Store_value(pred);
1305 ir_mode *predmode = get_irn_mode(predvalue);
1307 if(is_completely_overwritten(predmode, mode)
1308 || is_partially_same(predvalue, value)) {
1309 DBG_OPT_WAW(pred, store);
1310 exchange(pred_info->projs[pn_Store_M], get_Store_mem(pred));
1312 reduce_adr_usage(ptr);
1318 * We may remove the Store, if the old value already contains
1319 * the new value, and if it does not have an exception handler.
1321 * TODO: What, if both have the same exception handler ???
1323 if (get_Store_volatility(store) != volatility_is_volatile
1324 && !info->projs[pn_Store_X_except]) {
1325 ir_node *predvalue = get_Store_value(pred);
1327 if(is_partially_same(value, predvalue)) {
1328 DBG_OPT_WAW(pred, store);
1329 exchange(info->projs[pn_Store_M], mem);
1331 reduce_adr_usage(ptr);
1335 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
1336 value == pred_info->projs[pn_Load_res]) {
1338 * a Store of a value just loaded from the same address
1339 * -- a write after read.
1340 * We may remove the Store, if it does not have an exception
1343 if (! info->projs[pn_Store_X_except]) {
1344 DBG_OPT_WAR(store, pred);
1345 exchange(info->projs[pn_Store_M], mem);
1347 reduce_adr_usage(ptr);
1352 if (is_Store(pred)) {
1353 /* check if we can pass through this store */
1354 ir_alias_relation rel = get_alias_relation(
1356 get_Store_ptr(pred),
1357 get_irn_mode(get_Store_value(pred)),
1359 /* if the might be an alias, we cannot pass this Store */
1360 if (rel != ir_no_alias)
1362 pred = skip_Proj(get_Store_mem(pred));
1363 } else if (is_Load(pred)) {
1364 ir_alias_relation rel = get_alias_relation(
1365 current_ir_graph, get_Load_ptr(pred), get_Load_mode(pred),
1367 if (rel != ir_no_alias)
1370 pred = skip_Proj(get_Load_mem(pred));
1372 /* follow only Load chains */
1376 /* check for cycles */
1377 if (NODE_VISITED(pred_info))
1379 MARK_NODE(pred_info);
1382 if (is_Sync(pred)) {
1385 /* handle all Sync predecessors */
1386 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
1387 res |= follow_Mem_chain_for_Store(store, skip_Proj(get_Sync_pred(pred, i)));
1393 } /* follow_Mem_chain_for_Store */
1395 /** find entity used as base for an address calculation */
1396 static ir_entity *find_entity(ir_node *ptr)
1398 switch(get_irn_opcode(ptr)) {
1400 return get_SymConst_entity(ptr);
1402 ir_node *pred = get_Sel_ptr(ptr);
1403 if (get_irg_frame(get_irn_irg(ptr)) == pred)
1404 return get_Sel_entity(ptr);
1406 return find_entity(pred);
1410 ir_node *left = get_binop_left(ptr);
1412 if (mode_is_reference(get_irn_mode(left)))
1413 return find_entity(left);
1414 right = get_binop_right(ptr);
1415 if (mode_is_reference(get_irn_mode(right)))
1416 return find_entity(right);
1427 * @param store the Store node
1429 static unsigned optimize_store(ir_node *store) {
1434 if (get_Store_volatility(store) == volatility_is_volatile)
1437 ptr = get_Store_ptr(store);
1438 entity = find_entity(ptr);
1440 /* a store to an entity which is never read is unnecessary */
1441 if (entity != NULL && !(get_entity_usage(entity) & ir_usage_read)) {
1442 ldst_info_t *info = get_irn_link(store);
1443 if (info->projs[pn_Store_X_except] == NULL) {
1444 exchange(info->projs[pn_Store_M], get_Store_mem(store));
1446 reduce_adr_usage(ptr);
1451 /* Check, if the address of this Store is used more than once.
1452 * If not, this Store cannot be removed in any case. */
1453 if (get_irn_n_uses(ptr) <= 1)
1456 mem = get_Store_mem(store);
1458 /* follow the memory chain as long as there are only Loads */
1461 return follow_Mem_chain_for_Store(store, skip_Proj(mem));
1462 } /* optimize_store */
1465 * walker, optimizes Phi after Stores to identical places:
1466 * Does the following optimization:
1469 * val1 val2 val3 val1 val2 val3
1471 * Store Store Store \ | /
1478 * This reduces the number of stores and allows for predicated execution.
1479 * Moves Stores back to the end of a function which may be bad.
1481 * This is only possible if the predecessor blocks have only one successor.
1483 static unsigned optimize_phi(ir_node *phi, walk_env_t *wenv)
1486 ir_node *store, *old_store, *ptr, *block, *phi_block, *phiM, *phiD, *exc, *projM;
1488 ir_node **inM, **inD, **projMs;
1490 dbg_info *db = NULL;
1492 block_info_t *bl_info;
1495 /* Must be a memory Phi */
1496 if (get_irn_mode(phi) != mode_M)
1499 n = get_Phi_n_preds(phi);
1503 /* must be only one user */
1504 projM = get_Phi_pred(phi, 0);
1505 if (get_irn_n_edges(projM) != 1)
1508 store = skip_Proj(projM);
1510 if (!is_Store(store))
1513 block = get_nodes_block(store);
1515 /* abort on dead blocks */
1516 if (is_Block_dead(block))
1519 /* check if the block is post dominated by Phi-block
1520 and has no exception exit */
1521 bl_info = get_irn_link(block);
1522 if (bl_info->flags & BLOCK_HAS_EXC)
1525 phi_block = get_nodes_block(phi);
1526 if (! block_strictly_postdominates(phi_block, block))
1529 /* this is the address of the store */
1530 ptr = get_Store_ptr(store);
1531 mode = get_irn_mode(get_Store_value(store));
1532 info = get_irn_link(store);
1533 exc = info->exc_block;
1535 for (i = 1; i < n; ++i) {
1536 ir_node *pred = get_Phi_pred(phi, i);
1538 if (get_irn_n_edges(pred) != 1)
1541 pred = skip_Proj(pred);
1542 if (!is_Store(pred))
1545 if (ptr != get_Store_ptr(pred) || mode != get_irn_mode(get_Store_value(pred)))
1548 info = get_irn_link(pred);
1550 /* check, if all stores have the same exception flow */
1551 if (exc != info->exc_block)
1554 /* abort on dead blocks */
1555 block = get_nodes_block(pred);
1556 if (is_Block_dead(block))
1559 /* check if the block is post dominated by Phi-block
1560 and has no exception exit. Note that block must be different from
1561 Phi-block, else we would move a Store from end End of a block to its
1563 bl_info = get_irn_link(block);
1564 if (bl_info->flags & BLOCK_HAS_EXC)
1566 if (block == phi_block || ! block_postdominates(phi_block, block))
1571 * ok, when we are here, we found all predecessors of a Phi that
1572 * are Stores to the same address and size. That means whatever
1573 * we do before we enter the block of the Phi, we do a Store.
1574 * So, we can move the Store to the current block:
1576 * val1 val2 val3 val1 val2 val3
1578 * | Str | | Str | | Str | \ | /
1584 * Is only allowed if the predecessor blocks have only one successor.
1587 NEW_ARR_A(ir_node *, projMs, n);
1588 NEW_ARR_A(ir_node *, inM, n);
1589 NEW_ARR_A(ir_node *, inD, n);
1590 NEW_ARR_A(int, idx, n);
1592 /* Prepare: Collect all Store nodes. We must do this
1593 first because we otherwise may loose a store when exchanging its
1596 for (i = n - 1; i >= 0; --i) {
1599 projMs[i] = get_Phi_pred(phi, i);
1600 assert(is_Proj(projMs[i]));
1602 store = get_Proj_pred(projMs[i]);
1603 info = get_irn_link(store);
1605 inM[i] = get_Store_mem(store);
1606 inD[i] = get_Store_value(store);
1607 idx[i] = info->exc_idx;
1609 block = get_nodes_block(phi);
1611 /* second step: create a new memory Phi */
1612 phiM = new_rd_Phi(get_irn_dbg_info(phi), current_ir_graph, block, n, inM, mode_M);
1614 /* third step: create a new data Phi */
1615 phiD = new_rd_Phi(get_irn_dbg_info(phi), current_ir_graph, block, n, inD, mode);
1617 /* rewire memory and kill the node */
1618 for (i = n - 1; i >= 0; --i) {
1619 ir_node *proj = projMs[i];
1622 ir_node *store = get_Proj_pred(proj);
1623 exchange(proj, inM[i]);
1628 /* fourth step: create the Store */
1629 store = new_rd_Store(db, current_ir_graph, block, phiM, ptr, phiD);
1631 co_set_irn_name(store, co_get_irn_ident(old_store));
1634 projM = new_rd_Proj(NULL, current_ir_graph, block, store, mode_M, pn_Store_M);
1636 info = get_ldst_info(store, &wenv->obst);
1637 info->projs[pn_Store_M] = projM;
1639 /* fifths step: repair exception flow */
1641 ir_node *projX = new_rd_Proj(NULL, current_ir_graph, block, store, mode_X, pn_Store_X_except);
1643 info->projs[pn_Store_X_except] = projX;
1644 info->exc_block = exc;
1645 info->exc_idx = idx[0];
1647 for (i = 0; i < n; ++i) {
1648 set_Block_cfgpred(exc, idx[i], projX);
1652 /* the exception block should be optimized as some inputs are identical now */
1658 /* sixth step: replace old Phi */
1659 exchange(phi, projM);
1661 return res | DF_CHANGED;
1662 } /* optimize_phi */
1665 * walker, do the optimizations
1667 static void do_load_store_optimize(ir_node *n, void *env) {
1668 walk_env_t *wenv = env;
1670 switch (get_irn_opcode(n)) {
1673 wenv->changes |= optimize_load(n);
1677 wenv->changes |= optimize_store(n);
1681 wenv->changes |= optimize_phi(n, wenv);
1687 } /* do_load_store_optimize */
1690 typedef struct scc {
1691 ir_node *head; /**< the head of the list */
1694 /** A node entry. */
1695 typedef struct node_entry {
1696 unsigned DFSnum; /**< the DFS number of this node */
1697 unsigned low; /**< the low number of this node */
1698 ir_node *header; /**< the header of this node */
1699 int in_stack; /**< flag, set if the node is on the stack */
1700 ir_node *next; /**< link to the next node the the same scc */
1701 scc *pscc; /**< the scc of this node */
1702 unsigned POnum; /**< the post order number for blocks */
1705 /** A loop entry. */
1706 typedef struct loop_env {
1707 ir_phase ph; /**< the phase object */
1708 ir_node **stack; /**< the node stack */
1709 int tos; /**< tos index */
1710 unsigned nextDFSnum; /**< the current DFS number */
1711 unsigned POnum; /**< current post order number */
1713 unsigned changes; /**< a bitmask of graph changes */
1717 * Gets the node_entry of a node
1719 static node_entry *get_irn_ne(ir_node *irn, loop_env *env) {
1720 ir_phase *ph = &env->ph;
1721 node_entry *e = phase_get_irn_data(&env->ph, irn);
1724 e = phase_alloc(ph, sizeof(*e));
1725 memset(e, 0, sizeof(*e));
1726 phase_set_irn_data(ph, irn, e);
1732 * Push a node onto the stack.
1734 * @param env the loop environment
1735 * @param n the node to push
1737 static void push(loop_env *env, ir_node *n) {
1740 if (env->tos == ARR_LEN(env->stack)) {
1741 int nlen = ARR_LEN(env->stack) * 2;
1742 ARR_RESIZE(ir_node *, env->stack, nlen);
1744 env->stack[env->tos++] = n;
1745 e = get_irn_ne(n, env);
1750 * pop a node from the stack
1752 * @param env the loop environment
1754 * @return The topmost node
1756 static ir_node *pop(loop_env *env) {
1757 ir_node *n = env->stack[--env->tos];
1758 node_entry *e = get_irn_ne(n, env);
1765 * Check if irn is a region constant.
1766 * The block or irn must strictly dominate the header block.
1768 * @param irn the node to check
1769 * @param header_block the header block of the induction variable
1771 static int is_rc(ir_node *irn, ir_node *header_block) {
1772 ir_node *block = get_nodes_block(irn);
1774 return (block != header_block) && block_dominates(block, header_block);
1777 typedef struct phi_entry phi_entry;
1779 ir_node *phi; /**< A phi with a region const memory. */
1780 int pos; /**< The position of the region const memory */
1781 ir_node *load; /**< the newly created load for this phi */
1786 * Move loops out of loops if possible.
1788 * @param pscc the loop described by an SCC
1789 * @param env the loop environment
1791 static void move_loads_out_of_loops(scc *pscc, loop_env *env) {
1792 ir_node *phi, *load, *next, *other, *next_other;
1795 phi_entry *phi_list = NULL;
1797 /* collect all outer memories */
1798 for (phi = pscc->head; phi != NULL; phi = next) {
1799 node_entry *ne = get_irn_ne(phi, env);
1802 /* check all memory Phi's */
1806 assert(get_irn_mode(phi) == mode_M && "DFS geturn non-memory Phi");
1808 for (j = get_irn_arity(phi) - 1; j >= 0; --j) {
1809 ir_node *pred = get_irn_n(phi, j);
1810 node_entry *pe = get_irn_ne(pred, env);
1812 if (pe->pscc != ne->pscc) {
1813 /* not in the same SCC, is region const */
1814 phi_entry *pe = phase_alloc(&env->ph, sizeof(*pe));
1818 pe->next = phi_list;
1823 /* no Phis no fun */
1824 assert(phi_list != NULL && "DFS found a loop without Phi");
1826 for (load = pscc->head; load; load = next) {
1828 node_entry *ne = get_irn_ne(load, env);
1831 if (is_Load(load)) {
1832 ldst_info_t *info = get_irn_link(load);
1833 ir_node *ptr = get_Load_ptr(load);
1835 /* for now, we cannot handle Loads with exceptions */
1836 if (info->projs[pn_Load_res] == NULL || info->projs[pn_Load_X_regular] != NULL || info->projs[pn_Load_X_except] != NULL)
1839 /* for now, we can only handle Load(Global) */
1840 if (! is_Global(ptr))
1842 ent = get_Global_entity(ptr);
1843 load_mode = get_Load_mode(load);
1844 for (other = pscc->head; other != NULL; other = next_other) {
1845 node_entry *ne = get_irn_ne(other, env);
1846 next_other = ne->next;
1848 if (is_Store(other)) {
1849 ir_alias_relation rel = get_alias_relation(
1851 get_Store_ptr(other),
1852 get_irn_mode(get_Store_value(other)),
1854 /* if the might be an alias, we cannot pass this Store */
1855 if (rel != ir_no_alias)
1858 /* only pure Calls are allowed here, so ignore them */
1860 if (other == NULL) {
1865 /* for now, we cannot handle more than one input */
1866 if (phi_list->next != NULL)
1869 /* yep, no aliasing Store found, Load can be moved */
1870 DB((dbg, LEVEL_1, " Found a Load that could be moved: %+F\n", load));
1872 db = get_irn_dbg_info(load);
1873 for (pe = phi_list; pe != NULL; pe = pe->next) {
1875 ir_node *phi = pe->phi;
1876 ir_node *blk = get_nodes_block(phi);
1877 ir_node *pred = get_Block_cfgpred_block(blk, pos);
1880 pe->load = irn = new_rd_Load(db, current_ir_graph, pred, get_Phi_pred(phi, pos), ptr, load_mode);
1881 ninfo = get_ldst_info(irn, phase_obst(&env->ph));
1883 ninfo->projs[pn_Load_M] = mem = new_r_Proj(current_ir_graph, pred, irn, mode_M, pn_Load_M);
1884 set_Phi_pred(phi, pos, mem);
1886 ninfo->projs[pn_Load_res] = new_r_Proj(current_ir_graph, pred, irn, load_mode, pn_Load_res);
1888 DB((dbg, LEVEL_1, " Created %+F in %+F\n", irn, pred));
1891 /* now kill the old Load */
1892 exchange(info->projs[pn_Load_M], get_Load_mem(load));
1893 exchange(info->projs[pn_Load_res], ninfo->projs[pn_Load_res]);
1895 env->changes |= DF_CHANGED;
1899 } /* move_loads_out_of_loops */
1902 * Process a loop SCC.
1904 * @param pscc the SCC
1905 * @param env the loop environment
1907 static void process_loop(scc *pscc, loop_env *env) {
1908 ir_node *irn, *next, *header = NULL;
1909 node_entry *b, *h = NULL;
1910 int j, only_phi, num_outside, process = 0;
1913 /* find the header block for this scc */
1914 for (irn = pscc->head; irn; irn = next) {
1915 node_entry *e = get_irn_ne(irn, env);
1916 ir_node *block = get_nodes_block(irn);
1919 b = get_irn_ne(block, env);
1922 if (h->POnum < b->POnum) {
1933 /* check if this scc contains only Phi, Loads or Stores nodes */
1937 for (irn = pscc->head; irn; irn = next) {
1938 node_entry *e = get_irn_ne(irn, env);
1941 switch (get_irn_opcode(irn)) {
1943 if (is_Call_pure(irn)) {
1944 /* pure calls can be treated like loads */
1948 /* non-pure calls must be handle like may-alias Stores */
1951 /* cannot handle CopyB yet */
1955 if (get_Load_volatility(irn) == volatility_is_volatile) {
1956 /* cannot handle loops with volatile Loads */
1962 if (get_Store_volatility(irn) == volatility_is_volatile) {
1963 /* cannot handle loops with volatile Stores */
1972 for (j = get_irn_arity(irn) - 1; j >= 0; --j) {
1973 ir_node *pred = get_irn_n(irn, j);
1974 node_entry *pe = get_irn_ne(pred, env);
1976 if (pe->pscc != e->pscc) {
1977 /* not in the same SCC, must be a region const */
1978 if (! is_rc(pred, header)) {
1979 /* not a memory loop */
1985 } else if (out_rc != pred) {
1996 /* found a memory loop */
1997 DB((dbg, LEVEL_2, " Found a memory loop:\n "));
1998 if (only_phi && num_outside == 1) {
1999 /* a phi cycle with only one real predecessor can be collapsed */
2000 DB((dbg, LEVEL_2, " Found an USELESS Phi cycle:\n "));
2002 for (irn = pscc->head; irn; irn = next) {
2003 node_entry *e = get_irn_ne(irn, env);
2006 exchange(irn, out_rc);
2008 env->changes |= DF_CHANGED;
2012 /* set the header for every node in this scc */
2013 for (irn = pscc->head; irn; irn = next) {
2014 node_entry *e = get_irn_ne(irn, env);
2017 DB((dbg, LEVEL_2, " %+F,", irn));
2019 DB((dbg, LEVEL_2, "\n"));
2021 move_loads_out_of_loops(pscc, env);
2025 } /* process_loop */
2030 * @param pscc the SCC
2031 * @param env the loop environment
2033 static void process_scc(scc *pscc, loop_env *env) {
2034 ir_node *head = pscc->head;
2035 node_entry *e = get_irn_ne(head, env);
2037 #ifdef DEBUG_libfirm
2039 ir_node *irn, *next;
2041 DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
2042 for (irn = pscc->head; irn; irn = next) {
2043 node_entry *e = get_irn_ne(irn, env);
2047 DB((dbg, LEVEL_4, " %+F,", irn));
2049 DB((dbg, LEVEL_4, "\n"));
2053 if (e->next != NULL) {
2054 /* this SCC has more than one member */
2055 process_loop(pscc, env);
2060 * Do Tarjan's SCC algorithm and drive load/store optimization.
2062 * @param irn start at this node
2063 * @param env the loop environment
2065 static void dfs(ir_node *irn, loop_env *env)
2068 node_entry *node = get_irn_ne(irn, env);
2070 mark_irn_visited(irn);
2072 node->DFSnum = env->nextDFSnum++;
2073 node->low = node->DFSnum;
2077 if (is_Phi(irn) || is_Sync(irn)) {
2078 n = get_irn_arity(irn);
2079 for (i = 0; i < n; ++i) {
2080 ir_node *pred = get_irn_n(irn, i);
2081 node_entry *o = get_irn_ne(pred, env);
2083 if (irn_not_visited(pred)) {
2085 node->low = MIN(node->low, o->low);
2087 if (o->DFSnum < node->DFSnum && o->in_stack)
2088 node->low = MIN(o->DFSnum, node->low);
2090 } else if (is_fragile_op(irn)) {
2091 ir_node *pred = get_fragile_op_mem(irn);
2092 node_entry *o = get_irn_ne(pred, env);
2094 if (irn_not_visited(pred)) {
2096 node->low = MIN(node->low, o->low);
2098 if (o->DFSnum < node->DFSnum && o->in_stack)
2099 node->low = MIN(o->DFSnum, node->low);
2100 } else if (is_Proj(irn)) {
2101 ir_node *pred = get_Proj_pred(irn);
2102 node_entry *o = get_irn_ne(pred, env);
2104 if (irn_not_visited(pred)) {
2106 node->low = MIN(node->low, o->low);
2108 if (o->DFSnum < node->DFSnum && o->in_stack)
2109 node->low = MIN(o->DFSnum, node->low);
2112 /* IGNORE predecessors */
2115 if (node->low == node->DFSnum) {
2116 scc *pscc = phase_alloc(&env->ph, sizeof(*pscc));
2124 e = get_irn_ne(x, env);
2126 e->next = pscc->head;
2130 process_scc(pscc, env);
2135 * Do the DFS on the memory edges a graph.
2137 * @param irg the graph to process
2138 * @param env the loop environment
2140 static void do_dfs(ir_graph *irg, loop_env *env) {
2141 ir_graph *rem = current_ir_graph;
2142 ir_node *endblk, *end;
2145 current_ir_graph = irg;
2146 inc_irg_visited(irg);
2148 /* visit all memory nodes */
2149 endblk = get_irg_end_block(irg);
2150 for (i = get_Block_n_cfgpreds(endblk) - 1; i >= 0; --i) {
2151 ir_node *pred = get_Block_cfgpred(endblk, i);
2153 pred = skip_Proj(pred);
2154 if (is_Return(pred))
2155 dfs(get_Return_mem(pred), env);
2156 else if (is_Raise(pred))
2157 dfs(get_Raise_mem(pred), env);
2158 else if (is_fragile_op(pred))
2159 dfs(get_fragile_op_mem(pred), env);
2161 assert(0 && "Unknown EndBlock predecessor");
2165 /* visit the keep-alives */
2166 end = get_irg_end(irg);
2167 for (i = get_End_n_keepalives(end) - 1; i >= 0; --i) {
2168 ir_node *ka = get_End_keepalive(end, i);
2170 if (is_Phi(ka) && irn_not_visited(ka))
2173 current_ir_graph = rem;
2177 * Initialize new phase data. We do this always explicit, so return NULL here
2179 static void *init_loop_data(ir_phase *ph, const ir_node *irn, void *data) {
2184 } /* init_loop_data */
2187 * Optimize Loads/Stores in loops.
2189 * @param irg the graph
2191 static int optimize_loops(ir_graph *irg) {
2194 env.stack = NEW_ARR_F(ir_node *, 128);
2199 phase_init(&env.ph, "ldstopt", irg, PHASE_DEFAULT_GROWTH, init_loop_data, NULL);
2201 /* calculate the SCC's and drive loop optimization. */
2204 DEL_ARR_F(env.stack);
2205 phase_free(&env.ph);
2208 } /* optimize_loops */
2211 * do the load store optimization
2213 int optimize_load_store(ir_graph *irg) {
2216 FIRM_DBG_REGISTER(dbg, "firm.opt.ldstopt");
2218 assert(get_irg_phase_state(irg) != phase_building);
2219 assert(get_irg_pinned(irg) != op_pin_state_floats &&
2220 "LoadStore optimization needs pinned graph");
2222 /* we need landing pads */
2223 remove_critical_cf_edges(irg);
2227 /* for Phi optimization post-dominators are needed ... */
2228 assure_postdoms(irg);
2230 if (get_opt_alias_analysis()) {
2231 assure_irg_entity_usage_computed(irg);
2232 assure_irp_globals_entity_usage_computed();
2235 obstack_init(&env.obst);
2238 /* init the links, then collect Loads/Stores/Proj's in lists */
2240 irg_walk_graph(irg, firm_clear_link, collect_nodes, &env);
2242 /* now we have collected enough information, optimize */
2243 irg_walk_graph(irg, NULL, do_load_store_optimize, &env);
2245 env.changes |= optimize_loops(irg);
2247 obstack_free(&env.obst, NULL);
2249 /* Handle graph state */
2251 set_irg_outs_inconsistent(irg);
2252 set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);
2255 if (env.changes & CF_CHANGED) {
2256 /* is this really needed: Yes, control flow changed, block might
2257 have Bad() predecessors. */
2258 set_irg_doms_inconsistent(irg);
2260 return (int) env.changes;
2261 } /* optimize_load_store */